9514844 Larson-Prior The cerebellar cortex is an area of the brain known to receive multi-modal sensory information which it uses to organize appropriate motor outputs. Incoming sensory information is processed, in part, by neurotransmitters whose actions can be modulated by serotonin. At this time, the cellular mechanisms by which the cerebellar cortical circuit organizes and integrates incoming sensory data to produce appropriate motor commands are not well understood. In some systems, modulation of neurotransmission is known to produce a reorganization of the underlying circuitry which results in the generation of different neural responses. The ability of serotonin to effect such changes in the cerebellar cortical circuit will be examined in these studies. It is hypothesized that serotonin provides a global modulatory signal that is independent of the type of sensory data being processed. Thus, serotonergic input may signal changes in a global manner that is of equal relevance to all activated sensory systems. Under these circumstances, cells which project information to the cerebellum utilizing serotonin as a transmitter could regulate the level of motor response evoked by any given sensory signal dependent upon the state of the organism. By providing information on the manner in which serotonin modulates cerebellar processing, these studies will add significant new information concerning the mechanisms by which the brain coordinates and controls movement.
